1. Field of the Invention
This invention relates to a waterproof sheet fixing member for fixing a waterproof sheet to a structure to be waterproofed, and a method of fixing the waterproof sheet on the structure.
2. Description of Prior Art
Conventionally, in order to prevent rainwater from soaking into a structure such as a building or a house, a waterproof synthetic resin sheet is spread and fixed on the outer surface of the structure by an insulation method. The insulation method includes the steps of: fixing a plurality of waterproof sheet fixing discs made of a steel plate covered by a vinyl chloride film on the surface of the structure in a scattered manner by using anchors such as expandable nails or curl plugs; spreading a waterproof sheet made of synthetic resin or the like on the surface of the structure; and adhering the waterproof sheet to the fixing discs by using solvent (xe2x80x9csolvent adhering methodxe2x80x9d), heat (xe2x80x9cheat adhering methodxe2x80x9d), or glue (xe2x80x9cglue adhering methodxe2x80x9d).
However, the heat adhering method is not preferably from a viewpoint of safety because there is a possibility that a worker will get burned if the worker touches the heating source.
On the other hand, the solvent adhering method and glue adhering method are inferior in work ability and productivity because of the troublesome operations for coating the solvent or glue on the fixing discs. Furthermore, it is inevitable for the worker to breathe the chemical vapor of the solvent or glue during the coating operation. Thus, these methods are also not preferable from a viewpoint of safety.
Japanese Unexamined Laid-open Patent Publication No. H4(1992)-254649 (hereinafter referred to as xe2x80x9cJP4-254649xe2x80x9d) proposes a waterproof sheet fixing method which used no solvent or glue. The fixing method includes the steps of: fixing a fixing disc on a structure surface, wherein the fixing disc is made of a conductive plate such as a steel plate on which a thermoplastic resin layer is laminated; spreading a waterproof sheet so as to cover the fixing disc; and impressing a high frequency electromagnetic field to the fixing disc via the waterproof sheet to heat and melt the thermoplastic resin layer by the induction heating (i.e., eddy-current heating) so that the waterproof sheet is adhered to the fixing disc.
Another proposal has been made by Japanese Unexamined Laid-open Patent Publication No. H7(1995)-158395 (hereinafter referred to as xe2x80x9cJP7-158395xe2x80x9d). According to this proposal which also utilizes induction heating, a sheet fixing member includes a main body made of resin capable of being welded by heat to a waterproof sheet and an induction heat adhesive layer laminated on the upper surface of the main body. The induction heat adhesive material is a sheet-like member comprising resin capable of being welded by heat to the waterproof sheet and metal fibers or magnetic powders dispersed and mixed in the resin, or a sheet-like member comprising a metal film and resin layers capable of being welded by heat to the waterproof sheet, provided on both sides of the metal film.
In the aforementioned methods, since the high frequency induction heating is employed, there are the following advantages. The fixing operation of the waterproof to the fixing disc can be effectively performed in a short time. A worker never gets burned since no heating source is employed. Furthermore, a preferable working environment can be obtained since no solvent or glue is used.
However, the aforementioned prior arts have the following drawbacks.
The method disclosed in JP4-254649 employs a fixing disc comprising a conductive plate and a thermoplastic resin layer laminated on the conductive plate, as mentioned above. The conductive plate is usually made of metal such as steel or the like, and is not made of thermoplastic resin. Thus, the fixing disc is formed by laminating different materials, i.e., the conductive plate and the thermoplastic resin layer. As a result, the joining strength therebetween is generally low. Especially, it is difficult to obtain sufficient durability of the joining strength. Accordingly, the conductive plate and the thermoplastic resin may gradually separate as time passes, resulting in a gradual loss of fixing state of the waterproof sheet. Furthermore, in a case where [an] insulation is required to the structure to be waterproofed, an insulation layer is directly disposed on the surface of the structure. Since the insulation layer is generally made of material which is easily affected by heat such a polyurethane foam or polystyrene foam, the insulation layer may melt to be deformed due to the heat generated in the conductive plate. Accordingly, it is difficult to obtain the predetermined insulation performance.
On the other hand, according to one of the methods disclosed in JP7-158395 which employs the sheet-like fixing member comprising resin and metal fibers or magnetic powders dispersed and mixed therein, it is required that a large amount of metal fibers or magnetic powders is dispersed and mixed in the resin main body in order to securely fix the waterproof sheet to the sheet fixing member by the induction heating. However, this causes a heavy deterioration of strength of the sheet-like fixing member, resulting in an insufficient joining of the waterproof sheet to the sheet-like fixing member. Especially, it is difficult to obtain sufficient durability of the joining strength, resulting in a gradual loss of fixing status of the waterproof sheet.
According to the other method disclosed in JP7-158395 which employs a sheet fixing member including a sheet-like member comprising a metal film and resin layers capable of being welded by heat to the waterproof sheet laminated on both sides of the metal film, since different materials are laminated, the joint strength between the metal film and the laminated resin layer is generally low. Especially, it is difficult to obtain sufficient durability of the joint strength. Accordingly, the metal film and the laminated resin layer will be gradually separated as time passes, resulting in a gradual loss of fixing status of the waterproof sheet.
The present invention is made in view of the aforementioned technical background. It is an object of the present invention to provide a waterproof sheet fixing member and a method of fixing the waterproof sheet on a structure to be waterproofed by which a sufficiently strong and long lasting joint fixing status between the fixing member and the waterproof sheet can be obtained when they are welded by induction heating.
It is still other object of the present invention to provide a waterproof sheet fixing member for fixing a waterproof sheet on a structure to be waterproofed by induction heating, which causes less thermal deformation of a thermoplastic resin at a peripheral edge of the fixing member, regardless of a positional relationship between the fixing member and an induction heating device.
According to a first aspect of the present invention, a waterproof sheet fixing member for fixing a waterproof thermoplastic resin sheet on a structure to be waterproofed includes a plate-like main member made of a thermoplastic resin; and a conductive multi-aperture sheet having an upper surface and a lower surface, the conductive multi-aperture sheet having a plurality of apertures each communicating the upper surface with the lower surface, wherein the conductive multi-aperture sheet is integrally provided in the main member.
When fixing the waterproof sheet to the sheet fixing member, an eddy-current is generated in the conductive multi-aperture sheet due to high-frequency electromagnetic induction to cause direct heating of the waterproof sheet. The thermoplastic resin near the conductive multi-aperture sheet melts due to heat caused by the heating of the conductive multi-aperture sheet to cause the welding of the fixing member and the waterproof sheet. Both the resin of the waterproof sheet and that of the conductive multi-aperture sheet are directly welded by way of plurality of apertures formed in the conductive multi-aperture sheet, resulting in sufficient joint strength between the main member and the conductive multi-aperture sheet. Furthermore, since the resin near the conductive multi-aperture sheet provided in the fixing member is to be melted by the heat generated in the conductive multi-aperture sheet, almost no heat reaches the outer surface of the waterproof sheet, resulting in a good appearance of the waterproof sheet spread and fixed on the structure.
According to a second aspect of the present invention, a waterproof sheet fixing member for fixing a waterproof thermoplastic resin sheet on a structure to be waterproofed includes a plate-like main member made of thermoplastic resin, and a conductive multi-aperture sheet having an upper surface and a lower surface, wherein the conductive multi-aperture sheet has a plurality of apertures each communicating the upper surface with the lower surface. The conductive multi-aperture sheet is integrally provided in the main member. The fixing member further includes an anchor insertion hole provided at a central portion of the main member, a spacer provided on a lower surface of the main member so as to surround the anchor insertion hole, and a reinforcing protruded edge downwardly protruded from a peripheral edge of the main member.
With this waterproof sheet fixing member, by impressing a high frequency electromagnetic field with an oscillation surface of an induction heating device disposed on the fixing member via the waterproof sheet, a generation of heat occurs in the conductive multi-aperture sheet to heat and melt the main member made of thermoplastic resin near the sheet. The lower surface of the fixing member is hardly heated, and the reinforcing protruded edge is also hardly heated to effectively support the main member which is to be melted.
The spacer prevents a deformation of the fixing member even if an anchor nail is excessively inserted into the structure to which the waterproof sheet is to be fixed. This spacer and reinforcing protruded edge also prevent a deformation of the fixing member due to the pressing force of the high frequency induction heating device at the time of welding the waterproof sheet to the fixing member. This causes a flat surface of the fixing member. Since the conductive multi-aperture sheet is provided with a plurality of joining apertures, the sheet is strongly and integrally laminated to the main member, resulting in enhanced rigidity of the fixing member.
According to a third aspect of the present invention, a waterproof sheet fixing member for fixing a waterproof thermoplastic resin sheet on a structure to be waterproofed includes a plate-like main member made of thermoplastic resin, and a conductive multi-aperture sheet having an upper surface and a lower surface. The conductive multi-aperture sheet has a plurality of apertures each communicating the upper surface with the lower surface, wherein the conductive multi-aperture sheet is integrally provided in the main members. The fixing member further includes an anchor insertion hole provided at a central portion of the main member, and the main member is formed to have a curved upper surface.
With this waterproof sheet fixing member, by impressing a high frequency electromagnetic field with an oscillation surface of a high frequency heating device disposed on the fixing member via the waterproof sheet, a generation of heat occurs in the conductive multi-apertures sheet to heat and melt the main member made of thermoplastic resin near the sheet. At this time, the fixing member contacts the oscillation surface via the waterproof sheet in a state that a spherical surface (i.e., an upper surface of the fixing member) faces a flat surface (i.e., an oscillation surface). Therefore, the distance between the conductive multi-aperture sheet and the oscillation surface gradually increases toward outside from the contact point. In accordance with the increase of the distance, the generation of heat in the conductive multi-aperture sheet decreases. Thus, an excessive melting of the peripheral edge of the main member will not occur. Even if the oscillation surface contacts the fixing member in an inclined state, the relationship between the spherical surface and the oscillation surface contacted by the spherical surface maintains in the same manner as mentioned above. Since the conductive multi-aperture sheet applied to the fixing member is securely laminated to the main member and the fixing member has an upper spherical surface, the rigidity of the fixing member is enhanced.
According to a fourth aspect of the present invention, a method of fixing a waterproof thermoplastic resin sheet on a structure to be waterproofed, the method includes the steps of:
preparing a plate-like main member integrally provided with a conductive multi-aperture sheet, wherein the conductive multi-aperture sheet has a plurality of apertures each communicating an upper surface of the main member with a lower surface of the main member;
fixing the main member on a surface of the structure;
disposing the waterproof thermoplastic resin sheet on the surface of the structure; and
induction heating the conductive multi-aperture sheet via the waterproof thermoplastic resin sheet to melt a portion where the main member contacts the waterproof thermoplastic resin sheet so that the main member is integrally welded to the waterproof thermoplastic resin sheet.
According to the aforementioned method, the conductive multi-aperture sheet can be directly heated due to the high frequency electromagnetic induction action to melt the thermoplastic resin near the conductive multi-aperture sheet by the induction heating, whereby the main member and the waterproof sheet can be welded. Since the resin of the main member and that of the waterproof sheet are directly welded by way of the plurality of joining apertures provided in the conductive multi-aperture sheet, sufficient joining strength between the main member and the waterproof sheet can be obtained.